Recent trends in the epidemiology of shigellosis in Israel.

We provide an update on the epidemiology of shigellosis in Israel using data generated by a sentinel laboratory-based surveillance network for the period 1998-2012. The average annual incidence of culture-proven shigellosis was 97/100 000. We estimated that each case of shigellosis accounted for 25 cases in the community indicating the high burden of disease. Orthodox Jewish communities, living in highly crowded conditions and with a high number of children aged <5 years were the epicentre of country-wide biennial propagated epidemics of S. sonnei shigellosis. S. flexneri was the leading Shigella serogroup in Israeli Arabs. S. flexneri 2a and S. flexneri 6 alternated as the most common serotypes. Both S. sonnei and S. flexneri isolates showed high rates of resistance to ampicillin and trimethoprim/sulfamethoxazole and very low rates of resistance to quinolones and third-generation cephalosporins. Shigellosis due to S. sonnei conferred 81% (95% confidence interval 69-89) protection against the homologous Shigella serotype when epidemic exposure re-occurred 2 years later. These data are of value in the process of Shigella vaccine development.

Recent trends in the epidemiology of non-typhoidal Salmonella in Israel, 1999-2009.

The aim of the present study was to assess the recent trends in the epidemiology of non-typhoid Salmonella in Israel using a sentinel laboratory-based surveillance network. Between 1999 and 2009, 8758 Salmonella stool isolates were reported by five sentinel laboratories. There was a significant decrease in the incidence rate of Salmonella isolates from 70·5/100,000 in 1999 to 21·6/100,000 in 2005 followed by a slight increase to 30·3/100,000 in 2009. Of all Salmonella, 64·3% were isolated from children in the 0-4 years age group. Up to 2008, S. Enteritidis was the most prevalent serotype and in 2009 S. Infantis emerged as the most common Salmonella serotype. The decrease in the incidence of S. Enteritidis and S. Typhimurium and increase in S. Infantis among humans were associated with a similar trend among breeding flocks, which followed significant preventive interventions conducted against S. Enteritidis and S. Typhimurium infections in poultry. Tight surveillance and education of food handlers and consumers should be enhanced to reduce the foodborne transmission of Salmonella in Israel.

Epidemiology and clinical characteristics of patients with Staphylococcus saprophyticus bacteriuria in Israel.

BACKGROUND: Staphylococcus saprophyticus is a leading cause of lower urinary tract infections (UTI) in young women in the USA, Canada and Scandinavian countries, but seems to be very rare in other countries like Israel. The goal of this study was to investigate the incidence of S. saprophyticus in Northern Israel and to compare demographic and clinical characteristics of patients with S. saprophyticus and Escherichia coli bacteriuria. PATIENTS AND METHODS: Data from all patients with S. saprophyticus bacteriuria isolated in two major laboratories in northern Israel during a 1-year period were analyzed and clinical and epidemiological findings from 129 patients with S. saprophyticus bacteriuria were compared to that of 129 patients with E. coli bacteriuria. RESULTS: The incidence of S. saprophyticus in our region was 0.09% among all urine cultures requested. Patients with S. saprophyticus bacteriuria are mainly young women, more likely suffering asymptomatic bacteriuria, complain less of dysuria and burning and are less hospitalized than those infected with E. coli. Reported risk factors associated to S. saprophyticus bacteriuria such us seasonal variation, occupation in meat products industry, use of contraceptives, or sexual activity were not found by us. No nasal, vaginal, or rectal carriage was demonstrated. CONCLUSION: S. saprophyticus is a very uncommon urinary pathogen in Northern Israel. The natural reservoir of this uropathogen in our region remains unknown.

Atrial natriuretic peptide and endothelin concentrations in human milk during postpartum lactation.

Milk samples from lactating women (n = 24) were examined for atrial natriuretic peptide (ANP) and endothelin-1 (ET-1) content throughout the first 3 months postpartum. Samples were collected at the beginning (foremilk) and towards the end (hindmilk) of nursing. ANP was detected in the milk samples. A value of 9.4 +/- 1.8 pmol/l (mean +/- SEM) was observed on the third day postpartum. No significant variations in concentrations were observed during the 3 months examined. Foremilk and hindmilk ANP concentrations were also similar. ET-1, as previously reported, is present in the milk of lactating women. According to our observations, the concentration of ET-1 varies during the first 3 postpartum months. The highest concentrations were observed on the third day (10.2 +/- 1.8 pmol/l) of lactation, decreasing to 4.5 +/- 0.8 pmol/l after 1 week (p < 0.05) and to 2.0 +/- 0.3 pmol/l, at 1 month postpartum (p < 0.05), this level being maintained for up to 3 months postpartum. Foremilk samples on the third day postpartum contained significantly higher concentrations of ET-1, compared to hindmilk samples (10.2 +/- 1.8 vs 7.7 +/- 1.2 pmol/l, p < 0.05). The stable levels of ANP and the initial high and subsequently decreasing levels of ET-1 in human milk, during the first 3 months postpartum, suggest that these peptides might be of importance either in the lactating mammary gland or in the suckling newborn.

Biosynthetic threonine deaminase gene of tomato: isolation, structure, and upregulation in floral organs.

The gene encoding the plant biosynthetic threonine deaminase (Td; EC 4.2.1.16) has been cloned as a result of its unusual upregulation in tomato flowers. The Td gene of tomato encodes a polypeptide of 595 residues, the first 80 of which comprise a putative two-domain transit peptide cleaved at position 51. Comparison of the amino acid sequence with the corresponding enzymes from yeast and bacteria reveals a near identity of the important catalytic regions and greater than 40% overall similarity. The Td gene is unique in the tomato genome and its coding region is interrupted by eight introns. Its expression is greater than 50-fold higher in sepals and greater than 500-fold higher in the rest of the flower than in leaves or roots. Its overexpression, however, is strictly confined to the parenchymal cells of the floral organs. In young tomato leaves, the chloroplast-bound enzyme is found almost exclusively in the subepidermal spongy mesophyll cells.

Altered Phytochrome Regulation of Greening in an aurea Mutant of Tomato.

A brief pulse of red light accelerates chlorophyll accumulation upon subsequent transfer of dark-grown tomato (Lycopersicon esculentum) seedlings to continuous white light. Such potentiation of greening was compared in wild type and an aurea mutant W616. This mutant has been the subject of recent studies of phytochrome phototransduction; its dark-grown seedlings are deficient in phytochrome, and light-grown plants have yellow-green leaves. The rate of greening was slower in the mutant, but the extent (relative to the dark control) of potentiation by the red pulse was similar to that in the wild type. In the wild type, the fluence-response curve for potentiation of greening indicates substantial components in the VLF (very low fluence) and LF (low fluence) ranges. Far-red light could only partially reverse the effect of red. In the aurea mutant, only red light in the LF range was effective, and the effect of red was completely reversed by far-red light. When grown in total darkness, aurea seedlings are also deficient in photoconvertible PChl(ide). Upon transfer to white light, the aurea mutant was defective in both the abundance and light regulation of the light-harvesting chlorophyll a/b binding polypeptide(s) [LHC(II)]. The results are consistent with the VLF response in greening being mediated by phytochrome. Furthermore, the data support the hypothesis that light modulates LHC(II) levels through its control of the synthesis of both chlorophyll and its LHC(II) apoproteins. Some, but not all, aspects of the aurea phenotype can be accounted for by the deficiency in photoreception by phytochrome.

An NADH:quinone oxidoreductase of the halotolerant bacterium Ba1 is specifically dependent on sodium ions.

The rate of NADH oxidation by inverted membrane vesicles prepared from the halotolerant bacterium Ba1 of the Dead Sea is increased specifically by sodium ions, as observed earlier in whole cells. The site of this sodium effect is identified as the NADH: quinone oxidoreductase, similarly to the other such system known, Vibrio alginolyticus (H. Tokuda and T. Unemoto (1984) J. Biol. Chem. 259, 7785-7790). Sodium accelerates quinone reduction severalfold, but oxidation of the quinol, with oxygen as terminal electron acceptor, is unaffected. The sodium-dependent pathway of quinone reduction exhibits higher apparent affinity to extraneous quinone (Q-2) than the sodium-insensitive pathway, and is specifically inhibited by 2-heptyl-4-hydroxyquinoline N-oxide. ESR spectra of the membranes contain a feature at g = 1.98 which is tentatively identified as one originating from semiquinone. This feature is increased by NADH and decreased by addition of Na+, suggesting that, as proposed from different kinds of evidence for the V. alginolyticus system, sodium affects the semiquinone reduction step. As in the other system, the site of sodium stimulation in Ba1 probably corresponds to the site of sodium translocation, which was shown earlier (S. Ken-Dror, R. Shnaiderman, and Y. Avi-Dor (1984) Arch. Biochem. Biophys. 229, 640-649) to be linked directly to a redox reaction in the respiratory chain.

Functional characterization of the uncoupler-insensitive Na+ pump of the halotolerant bacterium, Ba1.

Respiration initiates Na+ efflux from Na+-preloaded cells of the halotolerant bacterium, Ba1. This efflux can take place against the concentration and electrochemical gradients. Since it is not inhibited by carbonylcyanide-p-trifluoromethoxyphenyl-hydrazone or N'N'-dicyclohexylcarbodiimide, it seems unlikely that either delta p (electrochemical potential difference of H+ across the membrane) generated by the primary proton pump or ATP play a role in the transduction of the energy supplied by electron transport. The electrogenic extrusion of Na+ causes passive counterflow of protons and/or simultaneous flux of permeant anions. In the absence of permeant anions the charge compensation attained by influx of protons is not complete. The membrane potential which persists in this case is inside negative and insensitive to uncoupler. The influx of protons builds up a delta pH of reversed sign (more acid inside), which is insensitive to uncoupler. The simultaneous efflux of Na+ and permeant anions diminishes the intracellular salt content and, as a corollary, causes volume contraction. Thus, the respiration-linked, uncoupler-insensitive Na+ pump may play a role in the regulation of the intracellular salt content.

Regulation of respiration by Na+ and K+ in the halotolerant bacterium, Ba1.

In the obligate aerobe, moderate halophile bacterium, Ba1, the ion composition of the medium was found to have a profound influence on the response of the respiratory system to changes in the external pH. In the pH range 6.5 to 8.5 the respiratory activity either increased or decreased progressively, depending whether K+ or Na+ ions were omitted from the medium. A nearly constant rate of respiration was observed in the entire pH range when both K+ and Na+ were present simultaneously. The stimulatory effect of Na+ was expressed especially in the alkaline pH range, where it induced acidification of the intracellular milieu. It was manifest in whole cells as well as in inverted membrane vesicles, and was not affected by either uncoupler or inhibitor of H+-ATPase. In contrast, the respiratory stimulation induced by K+ was most prominent in the acidic pH range and was accompanied by alkalinization of the internal pH. The effect of K+ was observed only in intact cells. Agents which interfered with energy transfer suppressed the effect of K+. With ethanol as the electron donor, Na+ was found to decrease the extent of reduction of the cellular NAD+ in the aerobic steady state, and to cause increased reduction of the cytochromes. K+ had no appreciable effect on the extent of reduction of any component in the respiratory chain. The implications of the above findings are discussed in relation to the mechanism(s) involved in the cation-mediated regulation of respiration and intracellular pH.

Uncoupler-stimulated Na+ pump and its possible role in the halotolerant bacterium, Ba.

In cells of Ba1 suspended in K salt as the osmoticum, the respiratory rate declined by 80% between the pH values of 6.5 and 8.5. Catalytic amounts of Na+ ions prevented this drop. The possibility that Na+ exerted its effect by an influence on proton fluxes across the membrane (Na+/H+ exchange) was explored. Addition of catalytic amounts of Na+ ions to cells respiring at pH 8.5 elicited an influx of protons and, as a result, the delta pH across the membrane became diminished. delta psi (membrane potential) was not affected by Na+. At pH 6.5, Na+ caused no proton influx. FCCP (carbonylcyanide-p-trifluoromethoxyphenylhydrazone) collapsed delta psi, but the Na+-dependent proton influx observed at pH 8.5 became enhanced, leading to an inversion of delta pH (more acid inside). When a Na salt was used as the osmoticum, delta pH of reversed polarity was generated by respiration also in the absence of FCCP. Respiring, inverted membrane vesicles responded to a Na+ pulse essentially as the intact cells. Based on the above and some additional findings it is suggested that these Na+-dependent effects are suited to prevent a raise in the intracellular pH over the level which hinders the respiratory activity. It may also play a role in the regulation of intracellular Na salt content.